Magnetic resonance imaging (MRI) is a type of scan used to look inside your body using magnetic fields and radio waves.
What is an MRI?
Magnetic resonance imaging (MRI) is an imaging technology that produces three-dimensional images of the inside of your body. It uses strong magnets and radio waves to generate signals from your body. These signals are then picked up by a radio antenna and processed by a computer to produce images. The MRI takes 15–90 minutes depending on which part of your body is being scanned.
Why is an MRI done?
An MRI is done to get a better, clearer look at your insides. It can also help avoid more unpleasant tests. It can detect many conditions especially around your eyes, ears, heart and circulatory system. It can also find torn ligaments, so is good for sports injuries.
It can be used to examine many parts of your body, including your:
- brain and spinal cord
- bones and joints
- heart and blood vessels
- internal organs, eg, liver, uterus or prostate gland.
An MRI scan can be done to help diagnose conditions, plan treatments and check how effective previous treatment has been.
How do I prepare for an MRI?
Food and drink before the scan
You may have to stop eating (fast) for a few hours before your MRI, but you will be told ahead of time if this is needed.
Your regular medicines
Take your prescribed medications as usual but if you are taking medicines that are patches, talk to your pharmacist or doctor to check if you need to remove this for the scan. Some patches contain metal which can cause skin burns or increased drug absorption from the patch.
Makeup and hairspray
Many makeup and hairspray products contain tiny metal particles so it is important that you do not wear any on the day of your scan.
Previous medical conditions
You will be asked some questions about your medical health, which may be mailed out to you before your appointment.
It is important to tell the radiology staff about any metal you have in your body including possible metal fragments in your eye and metal foreign bodies. Objects that have been implanted in your body need to be discussed ahead of the MRI scan as they may cause harm or be damaged. These include pacemakers, aneurysm clips, heart valve replacements, neurostimulators, cochlear implants, magnetic dental implants and drug infusion pumps.
An MRI scan is a painless and safe procedure. If you have a fear of small or enclosed spaces (claustrophobia) and think you might not be able to cope with the scan, talk to your doctor or the radiology service when you make your appointment. You may be given some techniques to help keep you calm or medicine to help you relax (a sedative). If you have arranged to have a sedative it can be provided by the radiology service on the day. However, you will need to arrive earlier than your appointment time to allow it to work. The radiology service will advise you on when you need to be there. A friend or whānau/family member will need to drive you home if you have taken a sedative.
During the MRI
During the procedure, you lie on a bed that slides into an open-ended tunnel with lights and sometimes a mirror. It is a noisy experience, so you will be given headphones and music to listen to which helps dull the noise. Nothing will touch you during the scan and you can talk to staff via an intercom.
You may be given an injection of contrast dye to make the scan easier to read. There are no risks although, rarely, some people may have a reaction to the contrast dye. Let your doctor know if you have reacted to any dyes in the past.
Your doctor or specialist will discuss the results of your scan with you.
Magnetic Resonance Imaging (MRI) Pacific Radiology NZ, 2011